Rick Smith, the warning coordination meteorlogist at the Norman, Okla., office of the National Weather Service, tells us the term was born on the fly in that same office "in response to an eerily similar situation on May 3, 1999."

"When that phrase was first used, it came about because of the need of the Weather Service to shake people and really grab their attention," Smith said. "We got lots of tornado warnings here. We needed a way to let them know that this was different."

Two forecasters who were in the Norman office in 1999 and again yesterday told The Oklahoman that when they saw the monster May 1999 storm, they knew they had to do something big, so they coined a new term.

"We used that the evening of the May 3rd because at the time it was an unprecedented event that we were looking at," Scott Curl, a senior forecaster, told the paper. "We had a large, violent tornado on the ground about to head into the most populous center in the state of Oklahoma and we were trying to make people aware that this was something different than normal. We were trying to do anything that we could at that time to get people's attention."

Smith said their office has issued tornado emergency warnings only a handful of times since 1999. Smith said the decision to issue the warning is made after a lot of deliberation. He compared it to launching a nuclear missile, where you want "two guys turning the key."

But, yesterday, the decision was "fairly easy." He said while it's hard to issue written guidance on when to issue such a dire warning; he said he tells colleagues that "you'll know it when you see it."

On Monday, the office issued a tornado warning at 2:40 p.m. CT; the tornado formed at 2:56 p.m. and at 3:01 p.m. the office made the decision to issue a "tornado emergency."

Moore — the area hardest hit by the tornado — received 36 minutes of warning before the tornado hit. Smith said the weather service had been warning of severe weather for "days and hours before that."

Unfortunately, and for reasons scientists still don't understand, a great number of people still died. Smith said he didn't want to say that sometimes it's about being at the wrong place at the wrong time.

But this tornado is in 99th percentile. That means that it will probably go down as one of the most powerful storms in recorded history. He said in that area of Oklahoma, where tornadoes are common, many people have safe rooms, storm shelters or basements.

"But sometimes, the tornado is just too much," Smith said. "If you have a tornado the intensity that we had yesterday, in some rare cases even doing the recommended actions may not be enough."